synonymous vs substitutable

synonymous and substitutable both are adjectives.

Word	Noun	Adjective	Verb	Adverb
synonymous	No	Yes	No	No
substitutable	No	Yes	No	No

synonymous (adjective)	substitutable (adjective)
(of words) meaning the same or nearly the same	capable of being exchanged for another or for something else that is equivalent
	(of words) interchangeable in a given context without changing the import of the expression